1. Field of the Invention
The present invention generally relates to treatment of sewage and, more particularly, is concerned with a method and arrangement for introduction of sewage pre-treatment at a site in a municipal sewage treatment system located upstream of a municipal sewage treatment facility of the system.
2. Description of the Prior Art
Municipal sewage (which, as used hereinafter, includes wastewater) collection, conveyance and treatment systems (hereinafter referred to as "sewage treatment systems") are extensive networks of interconnected pipeline infrastructure. Because of expansiveness and topography of municipal sewage treatment systems, sewage flows cannot always be conveyed by gravity. As a result, pumping sites are needed as part of the pipeline infrastructure to lift sewage flows over high points in the system or to the municipal treatment facilities.
A pumping site may be provided at a collection point of a project such as a housing development, an apartment complex development or a commercial office facility development The pumping site is used to pump untreated sewage collected from the development through a "force main" to a higher point where the untreated sewage can then flow by gravity to the municipal sewage treatment facility to be treated. The pumping site may also be provided at a point in the pipeline infrastructure where gravity flow is no longer able to deliver the untreated sewage to the sewage treatment facility due to the topography. The pumping site typically employs a collection sump receives and accumulates the untreated sewage from the upstream network of piping and a mechanical pump which then pumps the sewage from the collection sump through the force main to a higher point where the untreated sewage can flow by gravity to the sewage treatment facility to be treated. In a typical municipality, the sewage pipeline infrastructure of the sewage treatment system will contain numerous pumping sites to enable the flow of untreated sewage to reach the sewage treatment facility.
Odor control is understood to be the main problem in the sewer pipeline infrastructure of municipal sewage systems. Most odor producing compounds found in sewage result from anaerobic (without air) biological activity which consumes organic material, sulfur, and nitrogen found in the sewage. Organic odors are typically the result of biological activity that decomposes organic matter and forms a variety of malodorous gases.
At municipal sewage treatment facilities, sewage is typically treated using the processes of clarification, aeration and disinfection. The main additives in the treatment process are oxygen or air for biodegradation of the organics in the sewage and electrical power to operate pumps and compressors that deliver and mix the oxygen or air.
Due to expanding residential and commercial development the demands on municipal sewage treatment systems are ever increasing, requiring additional capital investment to meet the demands. However, the resources of municipalities are typically fee and tax based and consumed substantially by expenditures to cover current operating costs and oftentimes are insufficient to finance additional capital investments. Representative examples of various proposals to address this and other needs are those disclosed in U.S. Pat. No. 3,875,051 to Kovarik, U.S. Pat. No. 4,919,814 to Camahan et al., U.S. Pat. No. 5,332,502 to Wickens et al. and U.S. Pat. No. 5,807,484 to Couture et al.
However, none of these proposals appear to offer workable approaches for improvement of municipal sewage treatment systems without significant additional capital investment.
Consequently, a need still exists for innovation in connection with municipal sewage treatment systems which will increase the capacity of such systems with minimal additional capital investment.